Basic principles of generating horizontal saccades

Saccades are one of 5 types of eye movements. They are used to point your fovea quickly from one object of interest to another, such as the words of this sentence.

The command for a saccade begins in a structure called the Paramadian Pontine Reticular Formation; the PPRF

1. Burst neurons in the PPRF generate phasic movement command which is proportional to velocity
2. Tonic neurons in prepositus hypoglossi (PPH)
   • converts the phasic command to a tonic command
   • this is like an integrator which converts velocity to position
3. Motorneurons (MN's) combine phasic and tonic commands
   • this contracts muscles
   • quickly rotates the eyes (phasic component)
   • & then holds (tonic component) them there against the elastic restoring forces.